The present invention relates to a semiconductor device, a process of the production thereof and a microwave plasma treatment apparatus for use in the process. More specifically, it relates to a highly reliable semiconductor device for use in LSIs, a process for producing the semiconductor device at high yields, and a microwave plasma treatment apparatus suitable for forming a high-quality thin film on a substrate having a large area uniformly at a high rate or for carrying out an etching treatment uniformly at a high rate.
In a conventional semiconductor device, an insulating layer between connection pattern layers is a flat insulating layer which is formed by a chemical vapor deposition method (to be referred to as "CVD method" hereinafter) combined with sputtering as described in "SiO.sub.2 planarization technology with biasing and electron cyclotron resonance plasma deposition for submicron interconnections" (J. Vac. Sci Technol, B4 pp. 818 (1986)) and JP-A-60-91645 or by a method in which an SiO.sub.2 film is formed by a CVD method and then an SiO.sub.2 is formed by a coating method as described in "Interlayered Dielectric Planarization with TEOS-CVD and SOG" (Proc. V-MIC, p. 419 (1988)).
The arrangement in the above prior art disclosure have the following defects.
(1) In the CVD combined in sputtering arrangement when a sputter amount is large, an insulating material can be filled between pattern lines of an electrically conductive material forming a lower connection pattern layer without regard to connection pattern line intervals. However, where the line width is small, the insulating layer on the pattern is flattened and has a small thickness, and where the line width is large, the insulating layer on the pattern remains unflattened in some places and has a large thickness (see FIG. 2). Therefore, there arises a problem that an uneven etching occurs at an etching step for making through holes. Further, a portion of which the insulating layer has a thin thickness has high electric capacity and causes a wiring delay. PA1 (2) A film obtained by superimposed sputtering has a high compressive stress and therefore exerts a large stress on an electrically conductive material coated therewith. As a result, there arises a problem that the resultant semiconductor device is unreliable or that the film peels off. PA1 (3) When the sputter amount is small or when there is employed a method in which an oxide film is formed by a CVD process which is not combined no sputtering and the height difference is reduced with a coating such as a spin on glass film (to be referred to as "SOG film"), an insulating material is sufficiently filled between pattern lines only if the pattern line distance is large and if the aspect ratio is small. When the aspect ratio between the pattern lines exceeds 1, due to a first layer of a CVD film deposited by a CVD method, a portion to be filled with a second layer of an SOG film is very steep and has a larger aspect ratio, and an opening portion is also extraordinarily narrowed. As a result, there arises a problem that, even if an SOG film material having high fluidity is used, a void is liable to occur where the distance between pattern lines is small (see FIG. 3) to greatly reduce the reliability of the resultant semiconductor device. PA1 (4) The similar problem to that discussed in the above (3) also occurs not only in an insulating film between pattern layers but also in a portion where an outermost organic protection film having a steep height difference portion is formed. That is, a protection film is conventionally formed by a CVD process which is not combined no with sputtering. However, this method has a problem in that an organic packaging material cannot be filled between outermost connection pattern lines, which reduces the reliability. PA1 (5) Further, in a second aspect of the present invention, it is an object of the present invention to provide a microwave plasma treatment apparatus with which a high-quality thin film can be formed at a high rate and high-performance etching treatment can be carried out at a high rate and which also permits decreasing of the length in the central axis direction.
As a microwave plasma treatment apparatus, an apparatus as described in JP-A-63-217620 is known.
FIG. 34 shows a schematic view showing the cross section of the above conventional microwave plasma treatment apparatus.
In FIG. 34, numeral 301 indicates a substrate formed of silicon, Si, etc., numeral 302 indicates a substrate holder, numerals 303 and 304 indicate reaction gas feed lines, numeral 305 indicates a gas outlet, numeral 306 indicates a microwave inlet, numeral 307 indicates a microwave-introducing aperture, 309 indicates a vacuum chamber, 310 indicates a microwave guide tube, 311 indicates a magnetic field supply coil, and numerals 312 and 313 indicate gas feed ports.
The substrate 301 is placed on the substrate holder 302, and the substrate holder 302 is arranged within the vacuum chamber 309. A gas fed by one reaction gas feed line 303, e.g., oxygen, O.sub.2, is blown out into the vacuum chamber 309 from one gas feed port 312 through an annular gas-introducing path (not shown). On the other hand, a gas fed by the other gas feed line 304, e.g., monosilane, SiH.sub.4, is similarly blown into the vacuum chamber 309 from the other gas feed port 313 through an annular gas-introducing path (not shown). Microwave supplied by the microwave inlet 306 is introduced into the vacuum chamber 309 through the microwave guide tube 310 and the microwave-introducing aperture, and a magnetic field generated by the magnetic field supply coil 311 is supplied into the vacuum chamber 309. Further, gases formed after the reaction or unreacted gases are discharged out of the vacuum chamber 309 through the gas outlet 305.
In the above case, the gas feed port 312 which is one of the two gas feed ports is positioned considerably far from the above substrate 301, and the other gas feed port 313 is positioned in the vicinity of the substrate 301. Further, these gas feed ports have a constitution in which each has an aperture formed in parallel with the substrate 301 and gases are blown out from the gas feed ports 312 and 313 nearly in parallel with the substrate 301.
In the above-described conventional microwave plasma treatment apparatus, nothing has been taken into consideration concerning the relationship between the reaction process of a plurality of gases blown into the vacuum chamber 309 and the distances from the gas feed ports 312 and 313 to the substrate 301. Due to this, a plurality of the above gases sometimes react before these gases reach the substrate 301, and there arises a problem that in some cases no high-quality thin film is formed, or in some cases a high-performance etching treatment is not conducted uniformly. In particular, with an increase in that surface area of the substrate which is to be treated, the probability of occurrence of the above problem increases.
In addition to the above, the conventional microwave plasma treatment apparatus also has problem in that it has a useless space contributing to no reaction due to a considerably large length in the central axis direction.